Studies on the effects of cannabis (marijuana) have led to the recent discovery of an endogenous system of ligands in humans involved in a number of physiological processes including pain and inflammation. The main naturally occurring ligands for this system, anandamide and 2-arachidonoylglycerol (2-AG), activate a number of cannabinoid receptors, including CB1 and CB2 receptors. Like opioid receptors, CB1 and CB2 receptors are members of the G protein-coupled receptor superfamily. CB1 receptors and associated ligands are mainly localized in the brain whereas CB2 receptors are found mainly in peripheral tissues, particularly immune cells such as leukocytes and mast cells, which have been shown to be involved in pain and inflammatory responses. Cara is therefore developing lead molecules that selectively modulate peripheral CB2 receptors without targeting CNS cannabinoid receptors. Peripheral CB2 receptor modulators will be initially developed as a novel therapeutic approach for neuropathic pain, a condition currently without consistently effective therapies.

Cara's most advanced CB2 compound, CR859, is in preclinical development.